Estimation of Maternal Effects on Some Economic Traits of North Iranian Native Fowls Using Different Models

This study was conducted to investigate direct and maternal effects on some economic traits in north Iranian native fowls. Traits considered were body weight at 1 day of age (BW1), body weight at 8 weeks of age (BW8), body weight at 12 weeks of age (BW12), egg number (EN) during the first 12 weeks of laying period, egg weight at 1st day of laying (EW1), mean egg weight at 28th, 30th and 32nd weeks (MEW), age at sexual maturity (ASM) and weight at sexual maturity (WSM). The data were analyzed using Restricted Maximum Likelihood procedure fitting an animal model with DFREML software package. A series of six different animal models with and without maternal effects were fitted for all traits, and the best model for each trait was chosen based on log-likelihood ratio tests (LRT). The direct heritability (h2) estimates ranged from 0.03 (BW1) to 0.51 (MEW). Maternal effects were significant on all the traits studied. The estimates of maternal heritability (m2) ranged from 0.01 (BW8, WSM, ASM, EW1) to 0.15 (BW1), and the estimates of maternal environmental variance as a proportion of phenotypic variance (c2) varied from 0.02 (WSM, EW1, EN) to 0.23 (BW1). The correlations between direct and maternal additive genetic effects (ram) were negative for all traits. These results indicate that genetic selection schemes for body weight and egg traits should utilize models incorporating both direct and maternal effects.